Docker Swarm (mode) cluster

This section explains how to create a multi-host docker cluster with swarm mode using docker-machine and how to deploy Træfɪk on it.

The cluster constist of:

3 servers
1 manager
2 workers
1 overlay network (multi-host networking)

Prerequisites

You will need to install docker-machine
You will need the latest VirtualBox

Cluster provisioning

First, let's create all the nodes required. It's a shorter version of the swarm tutorial.

docker-machine create -d virtualbox manager
docker-machine create -d virtualbox worker1
docker-machine create -d virtualbox worker2

Then, let's setup the cluster, in order :

initialize the cluster
get the token for other host to join
on both workers, join the cluster with the token

docker-machine ssh manager "docker swarm init \
    --listen-addr $(docker-machine ip manager) \
    --advertise-addr $(docker-machine ip manager)"

export worker_token=$(docker-machine ssh manager "docker swarm \
join-token worker -q")

docker-machine ssh worker1 "docker swarm join \
    --token=${worker_token} \
    --listen-addr $(docker-machine ip worker1) \
    --advertise-addr $(docker-machine ip worker1) \
    $(docker-machine ip manager)"
docker-machine ssh worker2 "docker swarm join \
    --token=${worker_token} \
    --listen-addr $(docker-machine ip worker2) \
    --advertise-addr $(docker-machine ip worker2) \
    $(docker-machine ip manager)"

Let's validate the cluster is up and running.

docker-machine ssh manager docker node ls
ID                           HOSTNAME  STATUS  AVAILABILITY  MANAGER STATUS
2a770ov9vixeadep674265u1n    worker1   Ready   Active
dbi3or4q8ii8elbws70g4hkdh *  manager   Ready   Active        Leader
esbhhy6vnqv90xomjaomdgy46    worker2   Ready   Active

Finally, let's create a network for Træfik to use.

docker-machine ssh manager "docker network create --driver=overlay traefik-net"

Deploy Træfik

Let's deploy Træfik as a docker service in our cluster. The only requirement for Træfik to work with swarm mode is that it needs to run on a manager node — we are going to use a constraint for that.

docker-machine ssh manager "docker service create \
    --name traefik \
    --constraint=node.role==manager \
    --publish 80:80 --publish 8080:8080 \
    --mount type=bind,source=/var/run/docker.sock,target=/var/run/docker.sock \
    --network traefik-net \
    traefik \
    --docker \
    --docker.swarmmode \
    --docker.domain=traefik \
    --docker.watch \
    --web"

Let's explain this command:

--publish 80:80 --publish 8080:8080: we publish port 80 and 8080 on the cluster.
--constraint=node.role==manager: we ask docker to schedule Træfik on a manager node.
--mount type=bind,source=/var/run/docker.sock,target=/var/run/docker.sock: we bind mount the docker socket where Træfik is scheduled to be able to speak to the daemon.
--network traefik-net: we attach the Træfik service (and thus the underlined container) to the traefik-net network.
--docker: enable docker backend, and --docker.swarmmode to enable the swarm mode on Træfik.
--web: activate the webUI on port 8080

Deploy your apps

We can now deploy our app on the cluster, here whoami, a simple web server in Go. We start 2 services, on the traefik-net network.

docker-machine ssh manager "docker service create \
    --name whoami0 \
    --label traefik.port=80 \
    --network traefik-net \
    emilevauge/whoami"
docker-machine ssh manager "docker service create \
    --name whoami1 \
    --label traefik.port=80 \
    --network traefik-net \
    emilevauge/whoami"

Check that everything is scheduled and started:

docker-machine ssh manager "docker service ls"
ID            NAME     REPLICAS  IMAGE              COMMAND
ab046gpaqtln  whoami0  1/1       emilevauge/whoami
cgfg5ifzrpgm  whoami1  1/1       emilevauge/whoami
dtpl249tfghc  traefik  1/1       traefik            --docker --docker.swarmmode --docker.domain=traefik --docker.watch --web

Access to your apps through Træfɪk

curl -H Host:whoami0.traefik http://$(docker-machine ip manager)
Hostname: 8147a7746e7a
IP: 127.0.0.1
IP: ::1
IP: 10.0.9.3
IP: fe80::42:aff:fe00:903
IP: 172.18.0.3
IP: fe80::42:acff:fe12:3
GET / HTTP/1.1
Host: 10.0.9.3:80
User-Agent: curl/7.35.0
Accept: */*
Accept-Encoding: gzip
X-Forwarded-For: 192.168.99.1
X-Forwarded-Host: 10.0.9.3:80
X-Forwarded-Proto: http
X-Forwarded-Server: 8fbc39271b4c

curl -H Host:whoami1.traefik http://$(docker-machine ip manager)
Hostname: ba2c21488299
IP: 127.0.0.1
IP: ::1
IP: 10.0.9.4
IP: fe80::42:aff:fe00:904
IP: 172.18.0.2
IP: fe80::42:acff:fe12:2
GET / HTTP/1.1
Host: 10.0.9.4:80
User-Agent: curl/7.35.0
Accept: */*
Accept-Encoding: gzip
X-Forwarded-For: 192.168.99.1
X-Forwarded-Host: 10.0.9.4:80
X-Forwarded-Proto: http
X-Forwarded-Server: 8fbc39271b4c

Note that as Træfik is published, you can access it from any machine and not only the manager.

curl -H Host:whoami0.traefik http://$(docker-machine ip worker1)
Hostname: 8147a7746e7a
IP: 127.0.0.1
IP: ::1
IP: 10.0.9.3
IP: fe80::42:aff:fe00:903
IP: 172.18.0.3
IP: fe80::42:acff:fe12:3
GET / HTTP/1.1
Host: 10.0.9.3:80
User-Agent: curl/7.35.0
Accept: */*
Accept-Encoding: gzip
X-Forwarded-For: 192.168.99.1
X-Forwarded-Host: 10.0.9.3:80
X-Forwarded-Proto: http
X-Forwarded-Server: 8fbc39271b4c

curl -H Host:whoami1.traefik http://$(docker-machine ip worker2)
Hostname: ba2c21488299
IP: 127.0.0.1
IP: ::1
IP: 10.0.9.4
IP: fe80::42:aff:fe00:904
IP: 172.18.0.2
IP: fe80::42:acff:fe12:2
GET / HTTP/1.1
Host: 10.0.9.4:80
User-Agent: curl/7.35.0
Accept: */*
Accept-Encoding: gzip
X-Forwarded-For: 192.168.99.1
X-Forwarded-Host: 10.0.9.4:80
X-Forwarded-Proto: http
X-Forwarded-Server: 8fbc39271b4c